Such a side reflector lamp is described under the product designation “MINISTAR®” at the Internet domain www.osram.de. With this halogen incandescent lamp, a circumferential section of a lamp vessel is provided with a reflective coating such that a laterally arranged light-exit window remains on the lamp vessel, and this light-exit window makes it possible to use this lamp, for example, as a downlight, the lamp being mounted in the horizontal direction. Such reflector lamps have an extremely compact design and therefore require a minimum amount of installation space when they are installed.
This known design is significantly simpler than conventional reflector lamps, as are described, for example, in the European patent specification EP 0 495 194 B1. Such reflector lamps comprise a reflector, which is formed by a parabolic or ellipsoidal glass cap, and a halogen incandescent lamp which is fixed in the optical axis of the reflector.
It has been shown that the compact halogen incandescent lamps having a reflector integrated in the lamp vessel can be improved as regards the radiated luminous flux in particular when a luminous element which is accommodated in the lamp vessel is formed with at least two filament sections. Luminous elements having two filament sections are used, for example, in the case of halogen incandescent lamps envisaged for operation using the system voltage, as are described in the European patent specification EP 0 446 460 B1.